The proposed research is a continuation, and extension in new directions, of a long-term project aimed at establishing electrophysiological correlates of psychopathology. The ultimate goal is to advance understanding of brain mechanisms which may be deviant in psychiatric illness. The electroencephalogram (EEG) and various types of event related potentials (ERPs) are to be recorded. ERPs include sensory evoked potentials (EPs) in several stimulus modalities and slow potentials, such as the contingent negative variation (CNV) and motor potentials, obtained under various experimental conditions. In addition, impedance plethysmography, or rheoencephalography (REG), will be employed to obtain indices related to regional cerebral blood flow. All recordings are made from a number of scalp areas to provide information about topography and intra- and inter-hemispheric relationships. Basic hypotheses proposed that psychiatric disorder is associated with deviant patterning and spatial distribution of electrophysiological events, including alterations in normal hemispheric asymmetry. These hypotheses are supported by results so far obtained in this project, e.g., EEG and EP measurements relate differently in different major psychiatric diagnostic groups, and somatosensory EP topography differs in chronic schizophrenia. Blood flow studies in schizophrenia by other workers give findings concordant with the EP observations. Among the specific aims are: (a) to confirm and extend findings showing deviant patterning and topography of EPs in psychiatric illness; (b) determination of correlations between ERP and REG measurements, particularly with respect to diagnostic differences between psychiatric groups; (c) confirmation of deviant slow potential findings in psychosis; (d) ERP testing of different attention deficits in schizophrenia and affective psychoses; (e) testing hypotheses relating CNV to cortical exitation and prolonged negativity after CNV to cortical inhibition. Computer methods will be used to quantify the electrophysiological signals. Clinical populations, particularly patients with schizophrenias, affective disorders, personality disorders, and neuroses, will be compared with one another and with nonpatients.